/*
 * Copyright (c) 2019 Author: Fancyears Milos Malvis @1243093366@qq.com
 * ALL COPYRIGHT REVERSED.
 */

package com.fancyears.encrypt;

import com.auth0.jwt.JWTSigner;
import com.auth0.jwt.JWTVerifier;
import com.fasterxml.jackson.databind.ObjectMapper;

import java.util.HashMap;
import java.util.Map;

/**
 * @Author: Fancyears Milos Malvis
 * @Date: Created in  2019/5/22 16:30
 * @Modified By:
 */
    public class JWT {
        private static final String SECRET = "XX#$%()(#*!()!KL<><MQLMNQNQJQK sdfkjsdrow32234545fdf>?N<:{LWPW";

        private static final String EXP = "exp";

        private static final String PAYLOAD = "payload";

        //加密，传入一个对象和有效期
        public static <T> String sign(T object, long maxAge) {
            try {
                final JWTSigner signer = new JWTSigner(SECRET);
                final Map<String, Object> claims = new HashMap<String, Object>();
                ObjectMapper mapper = new ObjectMapper();
                String jsonString = mapper.writeValueAsString(object);
                claims.put(PAYLOAD, jsonString);
                claims.put(EXP, System.currentTimeMillis() + maxAge);
                return signer.sign(claims);
            } catch(Exception e) {
                return null;
            }
        }

        //解密，传入一个加密后的token字符串和解密后的类型
        public static<T> T unsign(String jwt, Class<T> classT) {
            final JWTVerifier verifier = new JWTVerifier(SECRET);
            try {
                final Map<String,Object> claims= verifier.verify(jwt);
                if (claims.containsKey(EXP) && claims.containsKey(PAYLOAD)) {
                    long exp = (Long)claims.get(EXP);
                    long currentTimeMillis = System.currentTimeMillis();
                    if (exp > currentTimeMillis) {
                        String json = (String)claims.get(PAYLOAD);
                        ObjectMapper objectMapper = new ObjectMapper();
                        return objectMapper.readValue(json, classT);
                    }
                }
                return null;
            } catch (Exception e) {
                return null;
            }
        }


}
